<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        function num() {
            var num = 0
            for (i = 0; i <= 100; i++) {
                num += i
            }
            alert(num)
        }
        //调用函数 调用几次执行几次
        num()
    </script>
</body>
</html>